1. Field of the Invention
This invention relates generally to mixing devices, and more particularly to static mixing devices disposed along a flowpath fed by plural sources.
2. Description of the Prior Art
A number of static mixing devices are known in the art which have static structures partially to obstruct the flow of materials in a stream flowing through the device, whereupon the materials follow a circuitous path to effect better mixing of the materials than is possible where material from plural sources is carried along an unobstructed passage. Examples of such devices include Horner, U.S. Pat. No. 4,093,188; Emele, et al, U.S. Pat. No. 4,632,568; Federighi, et al, U.S. Pat. No. 4,511,258; Kolossow, U.S. Pat. No. 4,431,311; and Rice, III, U.S. Pat. No. 4,408,893. Static mixing devices of this type have been used in resin dispensing devices wherein the resin and a curing agent feed the plural streams, such as that disclosed by Drake, U.S. Pat. No. 4,538,920. An example employing an adhesive dispensing gun is disclosed by Mandeville, et al, U.S. Pat. No. 4,643,336. These devices are rigid in construction and not convenient for small applications. Such devices are too expensive to be economically discarded after use, and therefore the user must thoroughly clean them after each use to prevent fouling of the flow channels through the device.
Many sealants and adhesives quickly become unworkable when they begin to cure. To maximize working time, these compositions are usually prepared from reactive components mixed just prior to application. A number of known devices are intended to store reactive components separately until the time of application. The reactive components exit through a common outlet or adjacent outlets, and are thus applied together to the surface that is being treated. Examples are disclosed in Hood, U.S. Pat. No. 3,980,222; Larkin, U.S. Pat. No. 4,548,606; Rado, U.S. Pat. No. 2,517,027; Reeves, Jr., U.S. Pat. No. 3,335,912; Schaeffer, U.S. Pat. No. 4,528,180; Schmitt, U.S. Pat. No. 3,866,800; Staar, U.S. Pat. No. 4,331,264; and Von Winckelmann, U.S. Pat. No. 4,099,651. These structures, although providing a common or adjacent outlet for the components, do not adequately mix the reactive components at the outlet to ensure a complete and properly controlled reaction or, in the case of adhesives, bonding. Many of the devices are also difficult and/or costly to manufacture.
Where two streams of reactive components are simply flowed together, the proportion of components is not correct. At the junction of the component masses, the proportion, for example, of curing agent to resin is too high, causing overly accelerated curing. Away from the junction, the proportion is too low (or even zero) and curing is too slow or is absent entirely.
It would be desirable to provide a static mixing device for reactive components or any other components to be mixed, which provides a nearly homogeneous mix of the components. The optimum device would be inexpensive to manufacture and disposable such that it could be supplied with a container for the components. It would therefore be desirable to provide an inexpensive static mixing device which could be used to separately store components such as reactive components of a desired composition, and which would thoroughly mix the components prior to or during discharge for use or application. It would further be desirable to provide a static mixing device which could be readily adapted to a variety of shapes and sizes, and such a device wherein a minimum quantity of the material becomes trapped in the mixing device and therefore is unusable.